1. Field of the Invention
The present invention relates to filter assemblies, and in particular, to a filter bag which is capable of maintaining the micron integrity of the filter media used when used in a pressurized filter system.
2. Discussion of the Relevant Art
In pressurized filter systems wherein filter bag assemblies are utilized, generally, a solid filter basket is used to support the filter bag since the filter media is unable to withstand the pressures under which the system operates.
A typical pressurized filter system is disclosed in U.S. Pat. No. 4,390,425 issued on June 28, 1983 to Peter T. Tafara. This type of construction is satisfactory for most applications. The rigid filter basket is provided with a plurality of holes therein and adequately supports the filter bag assembly while under pressure. Accumulation of residue occurs within the bag and when the bag is filled (reducing the fluid flow therethrough) the filter bag assembly is removed from the filter basket and replaced.
In many applications, in use today, the integrity of the filter media becomes critical in order to filter out minute particles from the fluid being filtered. The filter media must be capable of removing particles having micron ratings from 1 to 100 and, in addition, remove free and entrained, emulsified oil and grease within the fluid, which is being filtered under pressure. The filter assembly, which includes media manufactured of various types of material such as polyesters, fiberglass, etc., generally have micron ratings suitable for proper filtration. However, in the manufacture of the filter bag it has always been a problem to provide a seamed surface that does not have holes in it greater than the micron rating of the media. Conventionally, the filter bag assembly has been formed utilizing a sewing technique wherein the holes formed by the piercing sewing needle destroys the integrity of the filter media and a small amount of leakage through the needle holes allows particles to enter the downward stream of the filter bag assembly. In critical applications the needle holes destroy the usefulness of the filter. Many techniques of overlap, rollover, foldover, etc., have been attempted to overcome this problem, however, Applicant is not aware of any successful techniques heretofore.
Therefore, it is an object of the present invention to provide a filter bag assembly that maintains the integrity of the filter media utilized.
It is a further object of the present invention to provide a filter bag assembly that is inexpensive to manufacture and provides filtering capabilities under pressure to the limits of the media chosen.
It is a further object of the present invention to provide a filter bag assembly suitable for the use within pressurized filter housings.
It is still yet another object of the present invention to provide a method of manufacturing a filter bag assembly wherein the integrity of the media utilized is maintained.